1. Field of the Invention
The present invention relates to a seat slide apparatus, and more particularly to a seat slide apparatus comprising a lower rail mounted along a longitudinal direction of a vehicle floor surface and an upper rail guided and supported on the lower rail so as to freely slide in a longitudinal direction and mounted and fixed to a side of a seat main body.
2. Description of the Related Art
In general, a seat for a vehicle is provided with a seat main body constituted by a seat cushion, a seat back stood at the back thereof so as to be freely rotated and adjusted, and the like, and supports the seat cushion or the like constituting the seat main body on the vehicle body floor surface via a longitudinal slide mechanism, thereby being structured such as to be adjusted so as to freely slide in a longitudinal direction of the vehicle body and being formed so as to variously modify a layout of the seat within a passenger""s room.
Further, as a longitudinal slide mechanism for the seat mentioned above, there is employed a seat slide apparatus which is formed to be long in the longitudinal direction on the vehicle body floor surface, is mounted on the vehicle body floor surface and is constituted by a lower rail provided substantially in the same height as that of a surface of a floor carpet and an upper rail mounted and fixed to the seat main body.
As shown in FIGS. 1 and 2, in a conventional general seat slide apparatus 1, a pair of left and right lower rails 2 are provided with main body portions 2a made by a metal plate member and formed in a substantially upward-C shape, and a pair of left and right engagement portions 3 inward bent from front end sides of both of side portions 2b of the main body portions 2a and downward directed at front end sides, thereby forming opening portions 3a at end portions of the engagement portions 3.
A pair of left and right upper rails 5 in the seat slide apparatus 1 are formed in a substantially inverse-T shape so as to be assembled in the lower rails 2, and engaged portions are formed in both side portions upward bent from front end sides of horizontal portions in the upper rails 5. The engaged portions are assembled so as to be capable of engaging with the engagement portions 3 in the side of the lower rails 2.
Further, substantially inverse-T shaped vertical portions 5a of the upper rails 5 protrude upward from the opening portions 3a of the lower rail 2, and anchor members, shafts of a seat lifter, bases of a reclining mechanism and the like are mounted thereto. Rollers 7 are inserted between the lower rails 2 and the upper rails 5 by being supported by roller shafts 7a. 
When the rollers 7 are interposed between the lower rails 2 and the upper rails 5 so as to be slidably supported, as mentioned above, it is possible to at a certain level prevent problems that a sliding resistance is rapidly increased or reduced, that an abnormal noise at a time of operating, a malfunction due to a fluctuation of a sliding resistance caused by a load and the like are generated, and the like, in comparison with a conventional structure obtaining a sliding function on the basis of a simple slide between metal surfaces.
However, in the case that the conventional seat slide apparatus 1 as mentioned above is formed long, it is complex to work the respective portions, and there is a problem of rattle in the respective portions due to a size error or the like, so that there is a disadvantage that it is impossible to absorb a size dispersion in the vehicle and the respective portion of the seat. As shown in FIG. 2, when a slope is generated in the roller 2 between the lower rail 2 and the upper rail 5, there is a risk that a slide operating force is increased, whereby there is generated a trouble such that a smooth slide motion of the upper rail 5 can not be obtained.
Further, when setting a clearance to be large in order to prevent the sliding resistance from being increased, there is a risk that the rattle is generated, and it is necessary to select and fit rollers and sliders having different sizes due to the size dispersion of the respective slide parts, so that there is a disadvantage that a number of the parts is increased and a parts control becomes troublesome.
The present invention is made by taking the problems mentioned above into consideration, and an object of the present invention is to provide a seat slide apparatus which can absorb a size dispersion in a vehicle and respective parts of a seat, has a simple structure, requires no increase of a number of new parts and no additional operation, is inexpensive, can easily and rapidly execute a mounting operation, can obtain a smooth and stable sliding motion, and can reduce a sliding resistance so as to improve an operability.
According to a first aspect of the present invention, there is provided a seat slide apparatus comprising:
a lower rail mounted to be long in a longitudinal direction of a seat mounting floor surface; and
an upper rail guided and supported so as to freely slide in a longitudinal direction on the lower rail and mounted and fixed to a side of a seat main body,
wherein the lower rail is provided with a main body portion formed in a substantially upward-C shape and a pair of right and left upper side portions extended inward from front end sides of both side portions in the main body portion so as to form an opening portion, and roller receiving step portions are formed in both sides of a bottom portion in the main body portion,
wherein the upper rail has a main body portion formed in a substantially downward-C shape so as to be assembled in the lower rail, and a vertical wall protruding upward from a center of an upper wall in the main body portion and protruding upward from the opening portion of the upper side portion in the lower rail, and
wherein a roller is inserted between a step portion of the bottom portion in the main body portion of the lower rail and the upper wall in the main body portion of the upper rail, the roller is pivoted to roller shafts mounted to both side portions in the main body portion of the upper rail, and separated into right and left sections at a substantially center portion of the roller, and both side portions of the roller are mounted to the step portion of the bottom portion is the main body portion of the lower rail.
Further, in addition to the structure mentioned above, the lower rail may be structured such that a circular arc surface is formed in the roller receiving step portion, and a slider receiving portion is formed in a lower surface side of the upper side portion, and further, in the seat slide apparatus in which the slider receiving portion is provided in an upper end of the upper wall in the upper rail main body, both side portions of the roller may be mounted on a taper surface downward inclined toward a center portion in a width direction formed in the step portion of the bottom portion in the main body portion of the lower rail. Further, both side portions of the roller may be formed so as to have a larger diameter than that of the center portion, or the structure may be made such that an elastic body is inserted to the center portion. Further, the elastic body may be constituted by an elastic washer.